CAIE A-Level Biology 12.1.1 Energy Needs in Living Organisms

Practise linking ATP hydrolysis to active transport, muscular or organelle movement and anabolic synthesis of DNA, proteins, lipids or polysaccharides.

Exam points

link ATP hydrolysis with active transport of named substances against gradients
identify cellular or muscular movement that requires ATP-driven molecular work
explain energy input for anabolic synthesis of DNA, protein, lipid or polysaccharide

[Maximum number: 4]

There are many mitochondria located in the presynaptic knobs of neuromuscular junctions and in the sarcomeres of muscle fibres of striated muscle.

Explain the need for many mitochondria in the presynaptic knobs and in the sarcomeres.

any four from:

1 mitochondria produce ATP ;

presynaptic knob

2 for production of, acetylcholine / ACh ;

3 for, making / moving, vesicles ; A exocytosis

sarcomere

4 active transport of $\mathrm{Ca}^{2+}$ into, sarcoplasmic reticulum ;

5 detachment of myosin heads / break cross bridge

or

allows myosin head to move back to original position ;

6 AVP ; e.g. ref. to sodium potassium pump / active transport of $\mathrm{Ca}^{2+}$ out of synaptic knob

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12.1.1—Energy needs in living organisms question 1